The United Nations AIDS agency, UNAIDS, says the number of people with AIDS is increasing, and it says there could be a rapid rise in the number of deaths in the next two decades. The agency released its study in advance of the annual world AIDS conference next week in Barcelona, Spain.

The U.N. AIDS report predicts that within the next 20 years, 68 million people will die because of AIDS in the 45 most affected countries, unless prevention and treatment efforts are expanded.

The report says the number of people contracting AIDS is not leveling off in the most heavily affected countries.

For example, it says that almost 39 percent of adults in Botswana are infected with HIV, the virus that causes AIDS, the highest infection rate of any nation in the world. Two years ago, the infection rate in Botswana was less than 36 percent.

The U.N. agency says similar increases were noted in several other nations where more than 20 percent of the adult population is infected with HIV.

The head of the U.N. agency's Africa department, Badara Samb, says young people aged 15-24 are at greatest risk for infection.

"Over 40 million people are living with HIV/AIDS," said the U.N. official. "If we do nothing, and the situation is just stable, if there are no more new infections, that means that in 10 years, we will be having 40 million deaths. This is more than the combined number of deaths caused by the two world wars."

The report also says that in some countries, HIV infection is increasing in parts of the population that earlier were not considered at serious risk.

For example, in China, HIV/AIDS previously was spread chiefly through injecting drugs with infected needles and through unsafe blood transfusions. But it says HIV in China now is also being spread through heterosexual contact.

The U.N. agency reports similar findings in Russia and in eastern Europe. UNAIDS expert Michel Carael says the virus now is being spread from drug users to the wider society.

"The possibility that this infection goes to the general population is supported by the incredible rise in sexually transmitted infection, showing that if you have in parallel an epidemic of sexually transmitted infection and HIV among drug users, you can expect an exploding situation," said Mr. Carael.

The report says infection rates also are accelerating in Indonesia and in parts of western and central Africa where, until recently, infection rates have been relatively steady.

The U.N. AIDS agency cites Uganda, Zambia and Thailand as nations where prevention programs have helped reduce the rate of new infections. It is calling for greater access to AIDS treatment in sub-Saharan Africa and for increased international funding to contain the AIDS epidemic.